1. Field of the Invention
The present invention relates to a scanning optical device applicable to an image forming device or the like, and a jitter correction method therefor.
2. Description of the Related Art
Image forming devices are known in which a photosensitive member is exposed to laser light to form an electrostatic latent image, and the electrostatic latent image is developed with toner and transferred onto recording paper to obtain an image. Such an image forming device is provided with a scanning optical device for exposing the photosensitive member to laser light. Generally, the scanning optical device deflects/scans laser light using a rotating polygonal mirror.
However, jitter occurs due to discrepancies among the reflection coefficients of the reflecting faces of the rotating polygonal mirror, or due to changes of the rotation period of the motor that drives the rotating polygonal mirror. As used herein, “jitter” refers to shifts of the exposure position in the main scanning direction on the photosensitive member.
Japanese Patent No. 2615668 proposes a method for reducing jitter by correcting the discrepancy among the reflection coefficients of the reflecting faces of a rotating polygonal mirror and the changes of the rotation period of the motor that drives the rotating polygonal mirror.
Japanese Patent No. 2615668 is directed to a monochrome image forming device. Recently, however, demand is growing for color image forming devices as well. Particularly, tandem type color image forming devices that employ a plurality of photosensitive members have the problem that jitter causes color shifting in the main scanning direction when toner images are superimposed.